Schild, Howard G. and Muthukumar, M. and Tirrell, David A. (1991) Cononsolvency in mixed aqueous solutions of poly(N-isopropylacrylamide). Macromolecules, 24 (4). pp. 948-952. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:SCHIm1991
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Abstract
The lower critical solution temperature (LCST) of poly(N-isopropylacrylamide)(PNIPAAM), prepared by an aqueous redox polymerization, was studied in the cononsolvent mixture of water and methanol by means of cloud-point and microcalorimetric measurements. The observed solution behavior was quite distinct from that of poly(vinylmethyl ether) in the same binary solvent. Other cononsolvents, including dioxane and tetrahydrofuran, yielded phase diagrams similar to those of PNIPAAM in water-methanol mixtures. Flory-Huggins ternary solution theory can explain the observed results only in terms of a change in the solvent-solvent interaction parameter (χ _(12)) in PNIPAAM solutions. We believe this to be physically implausible in the dilute (0.04%) solutions used in this work. Furthermore, we find in comparing our work with that of Hirotsu (Hirotsu, S. J . Chem. Phys. 1988,88, 427) that the behavior of PNIPAAM in water-methanol mixtures is strikingly insensitive to a 200-fold variation in polymer concentration. We suggest that perturbation of is not the origin of cononsolvency or of the gel collapse transitions reported by Hirotsu and by Tanaka and co-workers (Amiya,T.; Hirokawa, Y.; Hirose, Y.; Li, Y.; Tanaka, T. J . Chem. Phys. 1987, 86,2375)
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| Additional Information: | © 1991 American Chemical Society. Received January 25, 1990; Revised Manuscript Received August 1, 1990. This work was supported by a National Science Foundation Predoctoral Fellowship to Howard G. Schild and by a grant from the US . Army Research Office (DAAL03-88-K-0038). Registry No. 1, 25189-55-3; PVME, 9003-09-2; THF,109-99-9; water, 7732-18-5;methanol, 67-56-1;dioxane, 123-91-1. | |||||||||
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| Issue or Number: | 4 | |||||||||
| Record Number: | CaltechAUTHORS:SCHIm1991 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:SCHIm1991 | |||||||||
| Official Citation: | Cononsolvency in mixed aqueous solutions of poly(N-isopropylacrylamide) Howard G. Schild, M. Muthukumar, and David A. Tirrell Macromolecules 1991 24 (4), 948-952 | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 53519 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | Anne Hormann | |||||||||
| Deposited On: | 22 Jan 2015 22:21 | |||||||||
| Last Modified: | 03 Oct 2019 07:50 |
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